P3-07-33: Are Single Node Metastases More Common in Patients with Breast Cancer in the Sentinel Node Era?

Abstract

Abstract Background: The axillary recurrence rate after axillary lymph node dissection has been reported as approximately 3%. Since the introduction of sentinel node biopsy (SNB), it has become apparent that, there is a significant decrease in axillary recurrence, ranging from 0.26% to 0.9% in published literature. One of the concerns that arises from this data is that, the sentinel node may have been missed when routine axillary node clearance were being performed. The aim of this study was to compare the results of a cohort of patients who had an axillary staging procedure prior to the introduction of SNB (axillary clearance) with patients after the introduction of SNB in relation to the number who had only one positive node in the axilla. Methods: From June 2003 to November 2010 data was collected on demographics, histopathology and procedure performed. All patients with invasive breast cancer prior to April 2005 had an axillary node clearance (ANC) with either wide local excision or mastectomy. Since April 2005 all patients with invasive breast cancer had a SNB and patients with a positive sentinel node (SN) underwent ANC. Patients with a negative SNB had no further axillary surgery. Results: 702 patients had axillary node surgery between June 2003 and November 2010. 251 patients had axillary node clearance (pre SN period) and 451 had SNB (SN period). Average age was 57 years. 509 patients (156 in pre SNB period and 353 in post SNB period) had no nodal metastases. Amongst the 193 node positive patients, 100 had single node involvement. In the pre SNB period 33 (34.7%) patients had single node involvement, compared to 67 (68.3%) in SNB period. The histopathological type of cancer did not vary significantly between the one node positive, multiple node positive and node negative groups. Conclusion: Our study confirms a significant rise in patients with a single node positive in the sentinel node period. This could be due to the SLN being “missed” during surgery when an axillary node clearance was performed, which would explain the reported higher axillary recurrence rates in the pre sentinel node period compared to the sentinel node period. Another possibility is that the SN is undergoing more detailed histopathological assessment as there are fewer number of lymph nodes to be examined. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P3-07-33.